Assisted recording, using a radio frequency magnetic field assisted recording head, referred to herein as a recording head, can record on a magnetic recording medium that has high magnetic anisotropy by superposing a radio frequency magnetic field and a recording magnetic field.
A spin torque oscillator (STO) including an oscillation layer and a spin injection layer can generate a radio frequency magnetic field by applying current to the STO. This is because magnetization of the oscillation layer can oscillate itself. A magnetic pole can then generate a recording magnetic field.
A radio frequency magnetic field and a recording magnetic field can be efficiently superposed on the magnetic recording medium if the distance between the STO and the magnetic pole is short.
However, the radio frequency magnetic field, which is generated from the oscillation layer in the STO, can also be applied to the magnetic pole when the distance between the STO and the magnetic pole is short. This phenomenon can induce energy loss because magnetization of the magnetic pole is not stable. This energy loss can reduce a generation rate for the radio frequency magnetic field of the oscillation layer.